Medical Cannabis or Marijuana Impairment

  Medical Cannabis or Marijuana Impairment

Posted by CN Staff on October 05, 2005 at 07:11:41 PT
By Rick Bayer 
Source: Alternatives 

What Are the FactsDoes cannabis alone, inhaled eight or more hours before activities such as driving a vehicle or working with machinery, cause significant mental or motor impairment that might increase risk to self or others? This is the question, properly stated, that legislators should have considered during the session just ended.
Instead, during the 2005 legislative session, Oregon House Bill 2693 passed the Republican-controlled House. HB 2693 would allow employers to fire--without evidence of impairment--Oregonians who register with the Oregon Medical Marijuana Program and who use marijuana as medicine. Fortunately the house bill failed in a Democrat-controlled Senate committee after heated testimony, but this may be a temporary reprieve as this impaired piece of legislation will probably be introduced again in the next round.Marijuana as MedicineCannabis has been used to relieve pain for centuries throughout the world, including in the US, prior to the Cannabis Tax Act of 1937. Cannabis-like compounds are called cannabinoids. The cannabinoid that most affects mental status, the one that has "psychoactive" effects, is THC, or tetrahydrocannabinol. THC is a highly effective pain reliever, equal in efficacy to codeine. GW Pharmaceuticals has performed randomized double-blind placebo-controlled trials showing that Sativex (a cannabis extract now available in Canadian pharmacies) markedly improves pain. For more on Sativex, see Alternatives Magazine Spring 2005 issue: Perhaps the best summary regarding pain relief is from the prestigious Institute of Medicine; "In conclusion, the available evidence from animal and human studies indicates that cannabinoids can have a substantial analgesic effect."The Oregon Medical Marijuana Act (OMMA), passed in 1998, states, " . . . marijuana should be treated like other medicines." Once inside the body, THC acts identically whether it comes from herbal cannabis or from synthetic Food and Drug Administration-approved THC (Marinol, brand of dronabinol). Either way, the major psychoactive cannabinoid remains THC so let's examine how THC is metabolized and experienced by the human body.Marijuana and ImpairmentIn A Primer of Drug Action, pharmacologist Robert Julian, MD, PhD, wrote, " . . . absorption of inhaled drugs is rapid and complete. The onset of behavioral effects of THC in smoked marijuana occurs almost immediately after smoking begins and corresponds with the rapid attainment of peak concentrations in plasma. Unless more is smoked, the effects seldom last longer than 3 to 4 hours."In the Journal of Cannabis Therapeutics, Franjo Grotenhermen, MD, wrote, "Pulmonary [lung] assimilation of inhaled THC causes a maximum plasma concentration within minutes, while psychotropic effects [the "high"] start within seconds to a few minutes, reach a maximum after 15 to 30 minutes, and taper off within 2 or 3 hours."In summary, any mental or motor "impairment" is associated with the psychotropic effects (the "high"), and these effects are equally associated with pain relief. When the plasma THC levels return to low-levels at 3 hours and baseline around 4 hours after smoking marijuana, the high resolves, and so too does any impairment. This is important: no impairment after 3 or 4 hours from taking THC.Marinol is available only by mouth but the package insert warnings should be heeded regardless of whether a person uses Marinol or herbal THC. These include: WARNINGS: Patients receiving treatment with Marinol should be specifically warned not to drive, operate machinery, or engage in any hazardous activity until it is established that they are able to tolerate the drug and perform such task safely. This is sound advice.When a clinician monitors drug therapy--any drug therapy--s/he educates a patient through careful explanations of procedures (method of use and expected results), alternative therapies, and risks involved in using or not using a medicine. There are many medicines--prescription or nonprescription--that cause drowsiness or impairment. These include medicine for blood pressure, diabetes, arthritis, respiratory infection, allergies, mood stabilization, and pain. Good communication lessens risks of adverse drug reactions.Whether in a workplace or not, one should avoid impairment when driving, operating machinery, or engaging in any hazardous activity. If the goal is safety, there is no substitute for actual observation of performance because impairment can have many sources. Non-prescription medicines, acute illness, or sleep loss can result in impairment. Good communication between employees, supervisors, and employers lessens risk of impairment at work.With all of the above in mind, here is the crux of the problem so ineffectively addressed by the sponsors of House Bill 2693. The standard urine test for "marijuana" does not test for the psychoactive "parent drug", THC. It only tests for an inactive "metabolite" or breakdown product of THC. Even without physical evidence of impairment, inactive metabolites can be present for weeks to months after consuming cannabis. Less frequent users clear cannabis metabolites from their urine faster than regular users. The US Department of Transportation says, "While a positive urine test is solid proof of drug use within the last few days, it cannot be used by itself to prove behavioral impairment . . .". Here, even the federal government agrees urine drug testing does not prove impairment.Fact: There is no significant impairment beyond four hours after smoking herbal marijuana. Even the flight simulator data, often tortured by prohibitionists to yield whatever results they wish, can be summarized. Five flight simulator data studies between 1976 and 1991 yield mixed results usually showing impairment up to 4 hours but no significant impairment at 8 hours or longer after cannabis consumption.If the flight simulator testing machines are made difficult enough, then at least one researcher, Dr. Leirer, demonstrated what he called a carry-over or "hangover" effect up to 24 hours later. Such a hangover effect is also seen with commonly used medicines or alcohol. The purported hangover effect is described by Leirer as "very marginal" and is only detected in tests of "very complex human/machine performance". Comparable, subtle effects are reported at very low blood alcohol levels of 0.025% (25 milligrams of alcohol per 100 milliliters of blood). Even if a hangover effect can be measured by a researcher in persons using alcohol, marijuana, or prescription drugs 24 hours after ingestion of a drug, our laws for alcohol do not consider 0.025% significant impairment. This alleged hangover effect causes less impairment than the 0.04% level considered the safe level for commercial motor vehicle drivers and far less than 0.08%, the standard threshold for drunk driving. In other words, flight simulator data actually demonstrate smoked cannabis beyond 4 hours causes no significant impairment by currently accepted medical-legal standards.In light of confusing computer flight simulation data, other researchers study real motor vehicle accidents. In 2002, authors Gregory Chesher and Marie Longo concluded, "At the present time, the evidence to suggest an involvement of cannabis in road crashes is scientifically unproven". However they note this may only reflect the evolving science since testing for inactive urine metabolites does not prove impairment.Because urine metabolites do not indicate impairment, some scientists measure the parent drug responsible for impairment. Dr. Drummer measured blood THC levels in fatal crashes in Australia and noticed an association between high THC levels and risk of traffic fatality even in the absence of other drugs. Using forensic evidence he determined whether a driver is "culpable" or responsible for the fatal accident and correlated it to blood THC levels. Drummer and colleagues conclude, "Recent use of cannabis may increase crash risk, whereas past use of cannabis does not".Even if one supports using parent drug blood THC levels as a marker for impairment, it remains unclear how to define the gray area about what is "recent" versus "past" use of cannabis. This is because the THC level below which there is no impairment varies dramatically among individuals. Plus, the actual numbers of persons who have only THC in the blood and are involved in accidents is low so current studies lack the statistical significance necessary to draw firm conclusions.Since no culpability for fatal automobile crashes exists below blood levels of 10 nanograms per milliliter (ng/ml), those concerned about legislation suggest that any proposed thresholds be above 10 ng/ml of blood THC. For more information about legislative considerations see: You Are Going Directly To Jail: DUID Legislation: What It Means, Who's Behind It, and Strategies to Prevent It by Paul Armentano: study using coordination testing showed inevitable failure on field sobriety testing if blood THC levels were 25 to 30 ng/ml. But, many failed testing at 90 and 150 minutes after smoking even though plasma concentrations were rather low. The researchers had the foresight to conclude that "establishing a clear relation between THC plasma concentrations and clinical impairment will be much more difficult than for alcohol". This is because alcohol and THC are chemically different and are metabolized differently inside the body.With medical marijuana laws, we need research to show if there is a correlation between clinical impairment and blood THC levels. Daily cannabis users (like patients) can have levels as high as 6 to 10 ng/ml without clinical impairment even after 24 or more hours of abstinence. Most experts think it is premature to make firm conclusions about the proper threshold of blood THC as a marker for "Driving Under the Influence".SummaryThere is no scientific evidence showing significant impairment beyond four hours from smoking marijuana. There is no scientific evidence of increased risk of motor vehicle accidents beyond four hours after smoking marijuana. No physician would routinely condone medical use of cannabis or other sedating drugs at work. But, careful consideration of the recommendations in the Marinol package insert for synthetic THC preserves safety and would be consistent with medical treatment plans for other medicines that can impair. We have FDA-approved guidelines for synthetic THC and we should use these same guidelines for herbal THC.Registration in the Oregon Medical Marijuana Program should never be sole cause for termination of employment. Medical use of marijuana within Oregon law should be treated like medical Marinol, medical morphine, and other medications, both in and out of the workplace. It is discriminatory to fire an unimpaired worker whose only cause for job termination is registration with the Oregon Department of Human Services Oregon Medical Marijuana Program. Let us hope that we won't see the sequel of House Bill 2693 surface in the Oregon legislature next session, and if we do, let us work to defeat such misguided and damaging public policy. Richard “Rick” Bayer, MD is board-certified in internal medicine, a Fellow in the American College of Physicians (FACP), and practiced in Lake Oswego for many years. He is a co-author of: Is Marijuana the Right Medicine For You?, a chief-petitioner of the Oregon Medical Marijuana Act in 1998, and has appeared as a medical cannabis expert witness in Oregon state courts. His testimony against HB 2693 with referenced footnotes is available by contacting him at: ricbayer For additional references see: Alternatives (Eugene, OR)Author: Rick BayerPublished: October 5, 2005Copyright: 2005 Get Real Inc.Contact: editor alternativesmagazine.comWebsite: Medical Marijuana Archives

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Comment #4 posted by eco-man on October 14, 2005 at 06:00:39 PT
Only high doses of THC cause impairment
The bottom line seems to be that it takes high doses of the THC cannabinoid to reach a level of driving impairment similar to that of the legal limit for blood alcohol while driving. Most people do not smoke that much cannabis at one time. The danger seems to be when cannabis and alcohol are combined. *The Influence of Cannabis on Driving. B., Sexton F., et al. United Kingdom: TRL; 2000: pp. 110. The results from a study of different doses of cannabis and the influence on driving and driving related skills are reported. UK's Transport Research Laboratory (TRL). and A URL that you can use to remote load or hot link the image below: "One approach to deriving a legal limit for cannabis during driving has been to set the threshold to the level at which 50% of results show impairment. For alcohol, Berghaus showed a BAC [blood alcohol content] of 0.073% corresponded to impairment on 50% of 923 performance measures examined. The corresponding threshold for THC was 11ng/ml [11 nanograms of THC per milliliter of blood]. This is the closest estimate of dose equivalence to date, although there are recent, well-controlled studies which have not been included in such meta-analyses. A necessary research undertaking would be a thorough meta-analysis of results to date, using statistical measures of effect size related to dose."
 -- Quote above (emphasis added) is from the conclusion page of the 
UK Department of Transport report. Cannabis and driving: a review of the literature and commentary. and and The Berghaus info mentioned in the above quote is from his 1995 article:
*Behavioral Effects of Alcohol and Cannabis: Can Equipotencies be Established? 1995 by H.-P. Krüger and G. Berghaus Center for Traffic Sciences, University of Würzburg, Röntgenring 11, D-97070 Würzburg, Germany.
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Comment #3 posted by charmed quark on October 05, 2005 at 17:00:06 PT
Backdoor reillegalization of medical marijuana
That's all this legislature is, there is no other way to look at it. At least for those patients that can still work. I can't imagine how a majority of the Oregon house voted for this. I can only hope it was out of ignorance.-CQ
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Comment #2 posted by FoM on October 05, 2005 at 15:17:37 PT

Press Release from ASA
Local Bans on Medical Marijuana Dispensaries Draw Lawsuits; Press Conference Oct. 6 with Attorneys, Plaintiffs, Advocates at League of Cities ConventionOctober 5, 2005To: Assignment, City and State Desks Contact: Hilary McQuie, 510-333-8554 or Kris Hermes, 510-251-1856, ext. 307, both of Americans for Safe AccessSAN FRANCISCO, Oct. 5 /U.S. Newswire/ -– Lawsuits over local bans on medical marijuana dispensaries will greet some of the elected officials gathering in San Francisco for the annual League of California Cities conference. Americans for Safe Access (ASA), an Oakland-based medical marijuana patient-advocacy group, will be announcing legal action against three California cities on the opening day of the convention. The ASA press conference will be held at 12:30 p.m. on Thursday, Oct. 6, in front of the convention at Moscone Center West, 800 Howard St.The lawsuits filed against Concord, Pasadena, and Susanville follow ASA's lawsuit filed this April against the city of Fresno for permanently banning medical cannabis dispensing collectives, which the suit contends illegally restricts the rights of qualified patients and their primary caregivers under California law. Each lawsuit includes a prospective dispensary operator plaintiff and a patient plaintiff."These bans clearly conflict with state law," said Joe Elford, ASA chief counsel. "The biggest hole in the Compassionate Use Act was in not describing the distribution method by which those who need the marijuana are able to legally access their medicine. The legislative response to the electorate's charge was SB 420's legitimatization of dispensing collectives and cooperatives. Cities are beholden to both state law and to the well-being of their citizens."In order for the patient plaintiffs to currently obtain the medicine their doctor has recommended, they must drive to other cities that have condoned and regulated dispensaries for their citizens. There are over 120 known dispensing collectives (dispensaries) throughout California, however they are unevenly distributed and not easily accessible to all legal patients. For example, it is a seven hour drive from Susanville, one of the cities whose ban is contested by ASA, to the closest dispensing collective.State Attorney General Bill Lockyer recently issued an opinion affirming that municipalities may not restrict the protections afforded by the Compassionate Use Act and SB420 to qualified medical marijuana patients. To see this opinion, go to This is one of several legal opinions issued to clarify the legal rights and responsibilities of state officials since the U.S. Supreme Court ruled that state-legal patients can still be prosecuted under federal marijuana laws."We hope this litigation will help local officials realize that permanent bans are unacceptable not just legally but morally, since they punish the sick and suffering in their communities who mainly rely on dispensaries," said ASA Legal Campaign Director Kris Hermes. "We're here to guide them through the process of establishing reasonable and sensible regulations." ASA publishes a variety of legal and medical reference materials, and will have information to aid city officials available to all in attendance at the League of Cities meeting.Since Oakland established the first ordinance condoning and regulating dispensaries in early 2004, twenty-one other cities and counties have followed suit (see: for a list and links to the policies). Later in 2004, cities and counties began to establish moratoriums on dispensing in order to arrive at regulations. As of Oct. 6, there are at least fifty-six localities with moratoriums and thirteen with permanent bans.For interviews with plaintiffs, local counsel, ASA chief counsel, or advocates, please contact Hilary McQuie at 510-333-8554 or hilary

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Comment #1 posted by FoM on October 05, 2005 at 11:42:58 PT

Press Release from The Drug Policy Alliance
Activists Seek to Improve San Francisco's Medical Marijuana ID ProgramWednesday, October 5, 2005Medical marijuana activists believe that some proposed changes to San Francisco’s medical marijuana ID card program, currently set to take effect November 9, would be detrimental to patients, caregivers and physicians.Advocates are expected to attend a town hall meeting on the changes and make alternative recommendations to the city’s Board of Supervisors. The proposed changes include relocating the program to a potentially less convenient location, increasing the cost of the ID card, and most significantly, retaining paperwork submitted by applicants for up to one year. The current Department of Public Health policy is to give all paperwork back to the applicant after verifying that a physician has recommended medical marijuana to the patient. If these documents, which contain the names of recommending physicians, are held by the department, they could be subject so subpoena or seizure by federal officials. That risk would likely discourage many physicians from recommending medical marijuana."At a time when the Bush Administration is on the warpath against medical marijuana patients, it is incumbent on local and state officials to protect the medical privacy of those patients, their caregivers and physicians," said Daniel Abrahamson, Director of Legal Affairs for the Alliance.Medical marijuana activists hope to improve San Francisco’s medical marijuana ID program so that it can serve as a model program, as well as create pressure to improve the ID program at the state level.The town hall meeting on the changes has been scheduled for October 17 at or around 6 PM. Please see our website for details to follow next week.
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